1. Field of the Invention
This invention relates to luminaires and more specifically to latch and hinge mechanisms for fastening a removable panel, preferably the panel including a window, to a luminaire.
2. Description of the Prior Art
Luminaires are required to be both highly functional and artistically pleasing in their surroundings. These two qualities are not always entirely compatible. For example, it is highly desirable for a luminaire to be completely sealed so that the lamp operates in as nearly a dust-free and moisture-free environment as possible. Should the luminaire allow dust to collect therein, the light efficiency will be greatly reduced requiring high maintenance or cleaning cost. Extreme conditions can even cause shorting to occur, thereby reducing the length of life of the lamp or lamps within the fixture and degrading the electrical connections. Moisture accumulation can have the same effects. If dust and moisture-proofing the fixture were the only consideration, luminaires would be permanently sealed and there would be no removable panels.
However, luminaires must be readily and quickly accessible to permit changing of bulbs and for other maintenance purposes. To meet this requirement, the access panel must be equipped with latches that are quickly operable and operable without requiring special tools. One common type of latch that has been used in the past has been the trunk-type latch. This type of latch permits quick access without special tools and permits sealing or compression of a gasket between frame members to minimize dust and moisture entry.
However, a trunk-type latch does not externally conform to the profile of the luminaire and therefore is artistically unacceptable in many installations. Further, flush ceiling mounting of the luminaire, and other similar installation, make trunk latches functionally awkward if not impossible.
Screws have been used to provide both the gasket pressure installation feature and the flush mounting. However, screws do require a special tool, particularly inconvenient in an overhead installation. By using a wingnut and screw or other hand manipulated screw arrangement, the "flush" installation feature is lost. Further, screws and their receiving screw holes do strip out after a number of uses, requiring difficult and expensive maintenance to the overall luminaire.
A further shortcoming of all these prior art latching mechanisms is that they perform only the function of latching and not of hinging. That is, when they are removed or unlatched, the panel is disconnected. This is particularly unhandy in an overhead situation where it is awkward to handle a disconnected panel while at the same time trying to change out a light bulb. Therefore, the prior art mechanisms have required a hinging arrangement in addition to a latching mechanism when complete removal of the panel was to be avoided. When this was done, however, then it made complete removal of the panel, as is sometimes required, a cumbersome and time-consuming undertaking.
It is therefore a feature of this invention to provide a luminaire with an improved latch that conforms with the overall structure and which is easy to unlatch without special tools.
It is another feature of this invention to provide a luminaire with an improved latch that also functions as a hinge to permit removal of a panel secured therewith or alternatively to permit swinging of the panel to provide access to the luminaire for bulb changing and the like.
It is still another feature of this invention to provide an improved latch that is flush with the luminaire when in its closed position, which is operable without special tools and which provides a biasing pressure when secured to allow sealing of a gasket around the panel periphery.